No abstract

The objectives of some experiments are to compare the variances of two or more treatments, products, or techniques. If the investigator is more concerned about within-unit variances rather than between-unit variances, then a repeated measurement design is needed. We invoke a random effects model with heterogeneous within-unit variances for certain repeated measurement designs. We do not impose any distributional assumptions for the random effects, whereas we assume either a normal or multivariate t distribution for the random errors. We propose a partial likelihood analysis for population-based inference and individual-based inference. We illustrate the methodology with an example from a trial comparing serum cholesterol measurements from a routine laboratory analyzer to those of a standardized method.

We prospectively studied 47 consecutive patients with either seasonal or perennial allergic rhinitis or non allergic rhinitis in a general allergy clinic. A diagnostic questionnaire was administered Jor symptoms oj rhinitis and fibromyalgia, and patients were examined for tender points. A history of congestion was present in 91%, rhinorrhea in 87%, and postnasal drip in 83%. Forty-nine percent had a history of diffuse, aching pain. or tiredness Jor at least 3 months; 49% percent had 11 or more tender points; and 38% had both a history of widespread pain plus 11 or more tender points (the 1990 criteria oj the American College oj Rheumatology for fibromyalgia). This frequency is much higher than the expected 4 to 5% prevalence of fibromyalgia in a general population. Seventynine percent of all subjects were skin-test positive to inhalant allergens, but positive skin tests alone did not correlate with. the number of tender points or criteria for fibromyalgia. Rhinitis. rather than atopy, is associated with fibromyalgia and may be an underdiagnosed, but important causative factor.